/Engine/Source/Runtime/Landscape/Classes/LandscapeComponent.h
Returns the heightmap for this component and the edit layer specified by InLayerGuid. If InLayerGuid is invalid, returns the final (base) heightmap :
[UTexture2D](API\Runtime\Engine\Engine\UTexture2D) * GetHeightmap ( const [FGuid](API\Runtime\Core\Misc\FGuid) & InLayerGuid ) const